Deputy Attorney General Rod Rosenstein arrives on Capitol Hill in Washington, Thursday, May 18, 2017, for a closed-door meeting with Senators a day after appointing former FBI Director Robert Mueller to oversee the investigation into possible ties between Russian Federation and President Donald Trump's campaign.

Sen. Lindsey Graham said Thursday he believes the Justice Department's Russian Federation probe is "now considered a criminal investigation", comments he made following the all-senators' briefing with deputy Attorney General Rod Rosenstein.

President Donald Trump said he "respects" the Justice Department's decision to appoint a special counsel to handle its investigation into Russia's election hacking, but called the effort a "witch hunt" created to hurt his presidency.

Sen. Marco Rubio commented on President Trump's statement that the situation is a "witch hunt" as well saying, "He's entitled to his opinion but 'we are a nation of laws'".

Rosenstein told lawmakers he didn't want to infringe on newly appointed special counsel Robert Mueller, whom Rosenstein named this week to lead the probe of possible Trump campaign ties to Russian Federation. "There is no collusion". White House officials, including Vice President Mike Pence, initially said that Trump only fired Comey on Rosenstein's recommendation - a contention supported by Trump's signed termination letter to Comey, which cited Rosenstein's memo as the rationale to dismiss the director.

Trump also said he was close to selecting a new Federal Bureau of Investigation director to replace James Comey, whom he fired last week, and that former senator and one-time Democratic vice presidential candidate Joe Lieberman was among the top candidates. "He knew that Comey was going to be removed prior to him writing his memo", she said again.

Comey 'was very unpopular with most people, ' Trump asserted as he stood next to the Colombian president during the joint news conference. Director Robert Mueller as the investigation's special counsel. That was the initial point of today's briefing, which was on the books well before the special counsel announcement. If special counsel had not been appointed, then Democrats on the Hill would have continued their partisan investigative efforts and legislative obstruction with the hopes of retaking control of the Congress in 2018 and impeaching the president. "Now, the administration must provide him the resources and independent authority he needs to follow the facts wherever they lead".

After Comey's firing, Rosenstein initially drew the ire of Democrats on Capitol Hill, but he seemed to have regained some good faith after his appointment of Mueller, a move Democrats had been almost unanimous in supporting.

Former FBI director Robert Mueller's appointment as special counsel has been welcomed by politicians from both sides.

On Wednesday, the president reportedly interviewed four candidates for Comey's former position at the White House. He's right, and it would be hard to find many people with more investigative experience, integrity and respect from both sides of the aisle than Mueller.

"I would be very discouraged if somehow this new special prosecutor would preclude Jim Comey from testifying in public before our committee", he said.